Disclosed embodiments of the invention relate generally to building cladding materials, such as curtain walls, and more particularly to anchor systems for securing curtain walls to building structures.
Many buildings of current construction, particularly commercial buildings, derive no structural support from their exterior walls. These walls simply isolate the interiors of the buildings from the environment outside the buildings, and as such are called curtain walls. “Curtain wall” is a term typically used to describe a building facade which does not carry any dead load from the building other than its own dead load. These loads are transferred to the main building through connections, such as anchors, at floors or columns of the building.
A curtain wall is designed to resist air and water infiltration, wind forces acting on the building, seismic forces, and its own dead load forces. Curtain walls can include heavy wall types such as brick veneer and pre-cast concrete panels. Curtain walls are also typically designed with an extruded aluminum frame, although the first curtain walls were made of steel. The aluminum frame is typically filled with glass, which provides an architecturally pleasing building, as well as benefits such as daylighting and environmental control. Other common fills include stone veneer, metal panels, louvers, and operable windows or vents.
A typical curtain wall assembly 220 on a building structure 208 is shown in FIG. 1. A curtain wall assembly 220 comprises curtain wall sections 200 having multiple panels 202 arranged side-by-side and/or in tiers. The curtain wall assembly 220 also comprises structural members 204, called mullions, which separate and secure the curtain wall panels 202. The mullions 204 are secured to the building structure 208 by anchors 206. The anchors 206 secure the mullions 204 to structural components that form the frame of the building structure 208. The anchors 206 typically secure the mullions 204 to steel girders, columns or cast concrete decks. The curtain wall panels 202 are typically attached to the mullions 204 with fastening devices that may have a variety of configurations. Configuration of such fastening devices depends on the nature of the curtain wall panel 202 to be fastened.
Present building construction techniques include pouring concrete floors 210 and interior dividing walls throughout one level, and forming one level after another until a desired number of levels have been completed. At this stage, the anchors 206 are mounted to a concrete floor 210, or several floors, or the roof 212 of a building structure 208. Thereafter, an exterior shell of the building structure 208 is created by attaching the mullions 204 to the anchors 206, and then attaching curtain wall sections 200 to the mullions 204. Alternatively, the curtain wall sections 200 may be attached directly to the anchors 206.
A typical method for attaching curtain walls to a building structure is shown in FIGS. 2-5. With reference to FIG. 2, a portion of a building structure 120 (“building structure”) prior to attachment of a curtain wall is shown. The portion of the building structure 120 may be a roof or one of the floors of the building structure 120, having a horizontal top surface 124. The building structure 120 may have several top surfaces 124 and a series of supports 122.
The assembly of a curtain wall anchor system initially comprises providing a support with a concrete block-out assembly, generally designated by numeral 100. The assembly 100 is installed on a concrete pour stop 126, which is mounted on the top surface 124 of the building structure 120. The concrete pour stop 126 defines a space into which concrete would be poured. The assembly 100 typically comprises attaching a U-channel 102 to a stud 104. A wood/steel shim 105 may be provided under the stud 104 for leveling and/or other reasons. Then, a wood or foam block-out 108, which is typically made at the construction site, is placed or mounted over the U-channel 102. Thereafter concrete is poured into the concrete pour stop 126. Concrete, which may be reinforced by steel bars 110, would typically be poured up to a level indicated by numeral 128. The assembly 100 may be tied to the steel bars 110 for stability during pouring of the concrete. After the concrete is cured, the block-out 108 would be removed. Removal of the block-out 108 would create an opening 130 (FIG. 3) over the U-channel 102 for further construction of the anchor system.
In use, workers at the construction site would have to fabricate each support with a concrete block-out assembly 100 by first attaching the stud 104 to the concrete pour stop 126, typically by welding to shims 105 (if metal) and/or tying to steel bars 110. Then, the U-channel 102 would be welded or otherwise attached to the stud 104. The piece of wood or foam functioning as the block-out 108 would then have to be made and attached to the U-channel 102 to prevent the soon to be poured concrete from covering an area over the top of the U-channel 102. Prior to attachment of the block-out 108, internal surfaces and side opening of the U-channel 102 were typically filled with foam 106, or a similar material, to protect the internal surfaces and opening of the U-channel 102 from the soon to be poured concrete. The internal surfaces and opening of the U-channel 102 typically contained components for further construction of the anchor system, and, thus, had to be protected the from poured concrete.
A series of additional support(s) with concrete block-out assemblies 100 would then be constructed by the workers along an edge or edges of the building structure 120, as shown in FIG. 3. With reference to FIGS. 4 and 5, concrete 112 would then be poured to fill the concrete pour stop 126. Thereafter, all of the block-outs 108 would be removed by the workers to expose open areas 130 in the concrete 112, above the U-channels 102. The workers would then remove the foam 106 to expose an internal mechanism inside the u-channels 102 for affixing an anchor 114 and associated components to the u-channel 102. An example of such an internal mechanism is an internal engagement 117, for receiving a threaded T-bolt 116 as shown in FIG. 5.
After installation of the threaded T-bolt 116, the anchor 114 would then be attached to the threaded stud 116 by a nut 118, for example. The anchor 114 would typically have an engagement portion 115. In use, mullions and curtain wall sections would be attached to the anchors 114 via the engagement portions 115 to complete the building structure 120, as described above.
Typical methods and structures providing curtain wall anchor systems are deficient in several aspects. First, installation of the anchor system at the job site is very time consuming and thus expensive. Workers at the job site are required to manufacture wood or foam block-outs 108 for each anchor system 100. Workers are also required to attach studs 104, U-channels 102, fill the U-channels 102 with protective material 106, and then install the block-outs 108. After the concrete 112 is poured and the block-outs 108 are removed, the workers are required to clean the internal surfaces and openings of the U-channels 102, and thereafter attach anchors 114 and associated components to each anchor system 100. Such a procedure is time consuming and costly.
Moreover, the multiple installation steps discussed above have to be manually repeated for each anchor system, and often different workers perform the required labor for different anchor systems. This leads to inconsistent results, for example, due to all of the components, e.g., studs, U-channels, block-outs and anchors, having to be installed by different workers and usually under varying and stringent time requirements. As such, quality control varies and may be compromised.
With costs being at least partly dependent upon man hours involved and equipment used at a building construction site, there is a need to complete construction according to the building codes in the shortest possible time, and, if possible, reduce the amount of components used. Also, there is a need to achieve more consistent results in manufacturing and installation of the anchor assemblies. Thus, an installation-ready anchor system for improving efficiency and consistency is desired.